The present invention relates to a potential free actuation circuit for a pulse duration controlled electronic power switch employing a driver stage and at least one pulse transformer whose primary winding is connected to the output of a pulse duration modulation stage. Such an actuation circuit is described, for example, by J. Wustehube in Schaltnetzteile [Switching Network Components], published by Expert Verlag, Grafenau, 1979, at page 410, FIGS. 11.14.
Actuation circuits for electronic power switches, particularly MOS power switches, must be actuated without potential if there is a separation between the primary and secondary circuits. This should usually be effected with the least possible number of components and with good efficiency.
Potential free will means that there is no DC coupling between pulse duration stage and the driver stage of the electronic power switch and that there is an insulation between these two stages. Such a potential free actuation can be realised by using a pulse transformer.